Method for manufacturing printed circuit board

Abstract

A printed circuit board includes a first electrically conductive circuit pattern, a substrate layer, an adhesive sheet, and a second electrically conductive circuit pattern, which are arranged in the above described order. The printed circuit board includes a single layer electrically conductive circuit area. The adhesive sheet defines a first opening spatially corresponding to the single layer electrically conductive circuit area. The adhesive sheet includes a first inner sidewall surrounding the first opening. The second electrically conductive circuit pattern defines a second opening spatially corresponding to the single layer electrically conductive circuit area. The second electrically conductive circuit pattern includes a second inner sidewall surrounding the second opening. The first inner sidewall and the second inner sidewall are not completely coplanar.

What is claimed is: 
     
       1. A method for manufacturing a printed circuit board, comprising:
 providing a single side copper clad laminate, an adhesive sheet, and a copper foil sheet, the single side copper clad laminate comprising a copper foil layer and a substrate layer, the copper foil sheet comprising a removable area and a circuit area surrounding the removable area; 
 defining a first opening in the adhesive sheet, the adhesive sheet comprising a first inner sidewall surrounding the first opening; 
 jointing the adhesive sheet between the substrate layer of the single side copper clad laminate and the copper foil sheet, thereby obtaining a multilayer substrate, the first opening spatially corresponding to the removable area; and 
 converting the copper foil layer into a first electrically conductive circuit pattern by etching, removing the removable area off the copper foil sheet by etching to obtain a second opening, converting the circuit area of the copper foil sheet into a second electrically conductive circuit pattern by etching, the second electrically conductive circuit pattern comprising a second inner sidewall surrounding the second opening, the first inner sidewall and the second inner sidewall being generally but not completely coplanar. 
 
     
     
       2. The method of  claim 1 , wherein after the step of jointing the adhesive sheet between the substrate layer of the single side copper clad laminate and the copper foil sheet, and before the step of converting the copper foil layer into a first electrically conductive circuit pattern by etching, the method further comprises a step of forming at least one electrically conductive hole in the multilayer substrate for electrically connecting the copper foil layer and the copper foil sheet. 
     
     
       3. The method of  claim 1  wherein after the step of converting the copper foil layer into a first electrically conductive circuit pattern by selectively etching, the method further comprises a step of forming a first cover layer on the first electrically conductive circuit pattern and forming a second cover layer on the second electrically conductive circuit pattern, a portion of the first electrically conductive circuit pattern being exposed from the first cover layer. 
     
     
       4. The method of  claim 3 , wherein after forming a first cover layer on the first electrically conductive circuit pattern and forming a second cover layer on the second electrically conductive circuit pattern, the method further comprises a step of forming a nickel gold layer on the portion of the first electrically conductive circuit pattern, which is exposed from the first cover layer.